The present invention relates to a method and an apparatus for connecting a fuel hose. More specifically, the present invention relates to a fuel hose connection method that involves using a ring-shaped sealing member, a hard, pipe-shaped opposing member, and a fuel hose. The opposing member can be a pipe made of metal or resin. The fuel hose has an opposing member insertion section for ensuring a fluid-tight connection between the opposing member and the fuel hose. The present invention also relates to a fuel hose connection structure based on the fuel hose connection method.
U.S. Pat. No. 5,664,608 (EP 0591831 A2) discloses a conventional, multi-layer hose with an outer layer made of rubber. Except for a pipe insertion section, the inner perimeter surface of the hose has a thin inner layer made of a hard metal or resin material having low fuel permeability. The publication states that fuel seepage to the outside is adequately prevented since the section of the inner perimeter surface of the hose that contacts the fuel has an inner layer having low fuel permeability. The publication also states that the hard inner layer is not formed at the pipe insertion section of the hose. Therefore, the required force to insert the pipe is reduced, and there is a high degree of sealing at the pipe connection section. However, since a fixed amount of fuel seeps into the contact section between the inner layer and the pipe, this conventional hose does not provide low fuel permeability, which is required due to stricter regulations on fuel permeability and the like.
Japanese Laid-Open Patent Publication Number Hei 8-294979 shown in FIG. 1 discloses a fuel hose having a rubber protector 1 covering a fluorocarbon resin tube 2. A sealing rubber 3 having low fuel permeability is adhered by vulcanization to the inner perimeter surface of the pipe insertion section of the fluorocarbon resin tube 2. The publication states that the presence of the sealing rubber 3 in the fuel hose reduces the insertion force to insert the pipe and maintains good fuel sealing properties. The publication also states that lower fuel permeability can be achieved by extending the fluorocarbon resin tube 2 to the end of the fuel hose. However, since the pipe is inserted into the hard fluorocarbon resin tube 2 having the sealing rubber 3 on the inner perimeter surface, the pipe is difficult to insert since the required insertion force is very high. Also, the sealing rubber 3 is made of a rubber material having low fuel permeability which is expensive, thereby increasing the cost of the fuel hose. Furthermore, the vulcanized adhesion process used for preventing misalignment of the sealing rubber 3 when the pipe is inserted also increases the cost of the fuel hose.
The present invention provides a fuel hose having low fuel permeability when connecting to pipes and superior fuel sealing properties. The fuel hose of the present invention also reduces the insertion force required to insert the pipe and does not require special increases in cost. Additionally, the present invention provides a method and an apparatus for connecting the fuel hose. Furthermore, the present invention effectively handles the unavoidable degradation in fuel permeability and sealing properties due to aging of the material in the fuel hose connection structure.
A fuel hose of the present invention includes a hose tube and a straight opposing member insertion section. The hose tube is made of a rubber or elastomer, and the opposing member insertion section is located at an end of the hose tube. A sealing ring is inserted into and fits inside a ring-shaped groove located on a section of the inner perimeter surface of the opposing member insertion section which is located toward a center side of the fuel hose along the hose axis (i.e., away from the end of the fuel hose). A ring-shaped tongue piece having a sloped surface hangs over the ring-shaped groove. The tongue piece is located inward in the radial direction from a side wall of the ring-shaped groove that is located toward an end side of the fuel hose along the hose axis (i.e., toward the end of the fuel hose). A thin resin layer having low fuel permeability covers the inner perimeter surface of the ring-shaped groove, including the tongue piece, and the entire inner perimeter surface of the hose tube from the ring-shaped groove toward the center side of the fuel hose along the hose axis (i.e., away from the end of the fuel hose).
xe2x80x9cRing-shapedxe2x80x9d refers to a continuous shape extending over the entire perimeter of the hose tube or the hard, tube-shaped opposing member. xe2x80x9cA tongue piece having a sloped surface and hanging over the ring-shaped groovexe2x80x9d indicates a tongue piece, which has a sloped surface, with lip-shaped cross-section that increases gradually in size over the space of the ring-shaped groove as it extends toward the center side of the fuel hose along the hose axis (i.e. toward the end of the fuel hose).
The present invention provides the following advantages with regard to fuel sealing properties, low fuel permeability, and insertion force on the opposing member.
The sealing member typically provides the fuel sealing properties in fuel hose connection structures, but the sealing member requires a sufficient securing force to prevent misalignment when the hose is connected. As described above, Japanese Laid-Open Patent Publication Number Hei 8-294979 discloses a fuel hose in which the sealing rubber is adhered by vulcanization to the low fuel permeability resin layer to prevent the misalignment of the sealing rubber when the hose is connected. However, vulcanization increases the cost of the fuel hose.
The sealing ring of the present invention is tightly inserted into the ring-shaped groove to ensure a high securing force on the sealing ring and to prevent misalignment of the sealing ring. Thus, the sealing ring of the present invention has a very high securing force without requiring a special process such as vulcanization.
Furthermore, after the hard, tube-shaped opposing member is connected, the engagement projection of the opposing member of the present invention is tightly secured to the ring-shaped groove of the hose tube via the low fuel permeability resin layer and the sealing ring. As a result, the fuel sealing properties are especially good when the pipe is connected.
A thin, low fuel permeability resin layer of the present invention covers the inner perimeter surface of the ring-shaped groove and the entire inner perimeter surface of the hose tube from the ring-shaped groove toward the center side of the fuel hose along the hose axis (i.e., away from the end of the fuel hose). The thin, low fuel permeability resin layer covers not only the inner perimeter surface of the hose tube which contacts the fuel, but also the inner perimeter surface of the ring-shaped groove to which the opposing member is inserted. As a result, there is no risk of fuel leakage at the connecting section of the fuel hose between the low fuel permeability resin layer and the opposing member. Thus, the connecting section has low fuel permeability.
The hard, tube-shaped opposing member is inserted into the straight opposing member insertion section of the fuel hose according to the present invention. The presence of the hard, low fuel permeability resin layer increases the insertion force required to insert the opposing member. However, the resin layer is only formed at the ring-shaped groove, and most of the hose tube is formed from soft rubber or elastomer. As a result, the insertion force on the opposing member can be remain low.
According to another embodiment of the present invention, a fuel hose can include a rubber or elastomer hose tube and a straight opposing member insertion section formed at the end of the hose tube. A ring-shaped groove for inserting and fitting a sealing ring is located on the inner perimeter surface of the opposing member insertion section toward a center side of the fuel hose along the hose axis (away from the end of the fuel hose). A ring-shaped ring supporting section depressed toward the center side of the fuel hose along the hose axis (away from the end of the fuel hose) is located on the side wall of the ring-shaped groove toward the center side of the fuel hose along the hose axis (away from the end of the fuel hose). A thin, low fuel permeability resin layer covers the inner perimeter surface of the ring-shaped groove, including the ring-shaped ring supporting section, and an entire inner perimeter surface of the hose tube from the ring-shaped groove toward the center side of the fuel hose along the hose axis (away from the end of the fuel hose).
The present invention provides similar advantages for low fuel permeability and low insertion force on the opposing member. The securing force on the sealing ring is provided by tightly inserting the sealing ring into the ring-shaped groove, and fuel sealing properties are provided by tightly fitting and securing the engagement projection of the opposing member in the ring-shaped groove.
However, a securing force on the sealing ring is not provided from a tongue piece when the fuel hose is connected to the opposing member as described above. Instead, the ring-shaped ring supporting section provides especially strong support and secures the sealing ring when the fuel hose is connected to the opposing member. Thus, a very strong securing force on the sealing ring can be provided without the use of a special process such as vulcanized adhesion.
According to another embodiment of the present invention, the ring-shaped groove having a ring-shaped tongue piece can include a ring supporting section as described above.
The ring-shaped groove can have both the tongue piece and the ring supporting section. Thus, the securing force on the sealing ring is especially strong due to the combined advantages of the tongue piece and the ring supporting section. This embodiment of the present invention provides similar operations and advantages as the previously described embodiments.
According to another embodiment of the present invention, the ring-shaped groove can have a stopper projecting inward in the radial direction past the inner perimeter surface of the opposing insertion member. The stopper is located inward in the radial direction on the side wall of the ring-shaped groove located toward the center side of the fuel hose along the hose axis (away from the end of the fuel hose).
Therefore, when the fuel hose and the opposing member are connected, the hard, tube-shaped opposing member is pushed into the opposing member insertion section of the fuel hose until it abuts the stopper. Thus, the engagement projection of the opposing member can abut the sealing ring so that the engagement projection is tightly fitted to the ring-shaped groove. The fuel hose is easy to connect since there is no need to align the opposing member.
According to another embodiment of the present invention, a fuel hose can have a tube wall section of the opposing member insertion section having a ring-shaped groove as described in any one of (A)-(D) below:
(A) an outer perimeter section of the tube wall with the ring-shaped groove is thicker outward in the radial direction than the other wall sections;
(B) an inner perimeter section of the tube wall with the ring-shaped groove is thicker inward in the radial direction than the other wall sections;
(C) an inner perimeter section of the tube wall with the ring-shaped groove has a ridge projecting inward in the radial direction; and
(D) a clamp or a ring is tightly mounted on an outer perimeter section of the tube wall with the ring-shaped groove.
This embodiment of the present invention provides the advantages of any one of the previously described embodiments, such as a high securing force on the sealing ring, good fuel sealing properties, low fuel permeability when connecting the opposing member, reduced insertion force on the opposing member, and easy fuel hose connection. Furthermore, deterioration of fuel sealing properties over time is effectively prevented.
Rubber or elastomer hose tubes and sealing rings, which are made substantially of rubber or elastomer, are compressed by a certain amount when the hose is connected to the opposing member due to deterioration over time. This deterioration cannot be avoided and is especially noticeable when the fuel hose is used in a heated environment. As a result, the fuel sealing properties of the sealing ring described above can gradually decrease. However, (A)-(D) of the embodiment described above can be used in the tube wall with the ring-shaped groove in the opposing member insertion section. The advantages listed below can be provided. If two or more of (A)-(D) are combined, the resulting embodiment will provide combined advantages.
In (A) or (B), the rigidity at this section of the tube wall can be improved since the tube wall with the ring-shaped groove is thickened either outward or inward in the radial direction. As a result, good fuel sealing properties can be maintained despite the deterioration of the hose tube and the sealing ring. In (B), the thickening of the tube wall reduces the depth of the ring-shaped groove, thereby decreasing the securing force on the sealing ring when the opposing member is inserted. Therefore, (A) or (C) are relatively preferable.
In (C), the sealing ring can be firmly secured by having a ridge projecting inward in the radial direction from the inner perimeter section of the tube wall with the ring-shaped groove. Furthermore, the ridge will slightly protrude into the sealing ring. Thus, high fuel sealing properties are maintained along the ridge even if the hose tube or the sealing ring deteriorates.
In (D), when a ring is mounted tightly on the outer perimeter section of the tube wall with the ring-shaped groove, a strong tightening stress is applied by the ring when the opposing member is inserted. Thus, even if the hose tube or the sealing ring deteriorates, the tightening stress from the ring can maintain good fuel sealing properties. When using a clamp, the clamp can be mounted in an untightened state on the outer perimeter section of the tube wall with the ring-shaped groove, and then the clamp can be tightened after the opposing member is inserted. Otherwise, the tightened clamp would provide resistance to the insertion of the opposing member. By tightening the clamp after inserting the opposing member, insertion is easier. By tightening the clamp, the same advantages as provided by the ring described above can be provided.
Furthermore, after tightening the hose tube to the opposing member of the fuel hose, external forces may deform the tightened section of the hose tube. In such cases, any one of (A)-(D) provides strong resistance to deformation in the tightened section of the hose tube, thereby preventing one-time or continuous disruption in fuel sealing properties.
According to another embodiment of the present invention, the ring-shaped groove can be shaped to match a ring-shaped sealing ring having a fixed, belt-type axial width. The thickened section described in (A) or the ridge described in (C) can be located on the section of the tube wall with the ring-shaped groove so that the thickened section or ridge aligns with the apex of the ring-shaped engagement projection which projects from the opposing member.
The ring-shaped sealing ring with a fixed belt-shaped axial width has especially high sealing pressure when aligned with the engagement projection on the opposing member. When the opposing member is inserted, the thickened section from (A) or the ridge from (C) is disposed on the section of the tube wall with the ring-shaped groove so that the thickened section or ridge aligns with the apex of the ring-shaped engagement projection on the opposing member to be inserted. This embodiment provides improved rigidity in the tube wall as described above and a secure insertion of the ridge in the sealing ring.
According to another embodiment of the present invention, a section of the hose tube located toward the center side of the fuel hose along the hose axis (away from the end of the hose tube) relative to the opposing member insertion section is formed as one of (1)-(3) below:
(1) a straight tube;
(2) a tube with at least one bend; and
(3) a straight tube or a tube with at least one bend where at least one section is a corrugated tube.
The fuel hose can be formed in any shape apart from forming a straight opposing member insertion section at the end of the hose tube.
According to another embodiment of the present invention, an outer perimeter of the hose tube of a fuel hose can have one or two of elements (a)-(d) below:
(a) a resin layer;
(b) a reinforcement thread layer;
(c) a thin metal film layer or metal laminate layer; and
(d) a rubber or elastomer outer protector layer.
The fuel hose has a rubber or elastomer hose tube and a thin, low fuel permeability resin layer, but other hose elements can be included on the outer perimeter of the hose tube, if necessary.
The present invention also provides a method for connecting fuel hoses including a step for tightly inserting and fitting a sealing ring into the ring-shaped groove of a fuel hose as described above and a step for inserting a hard, tube-shaped opposing member into the fuel hose. The opposing member has an ring-shaped engagement projection projecting from an outer perimeter surface of the opposing member. The engagement projection is located at an end or near an end of the opposing member. The opposing member is inserted so that the engagement projection abuts the sealing ring.
The operation and advantages of the fuel hose connecting method according to the present invention will be described using FIGS. 2a-2d. The fuel hose 4 shown in FIGS. 2a-2d includes a ring-shaped groove 6 of an opposing member insertion section 5. The ring-shaped groove 6 includes a tongue piece 7, a ring supporting section 8, and a stopper 9. A thin, low fuel permeability resin layer 10 covers the entire inner perimeter surface from the ring-shaped groove 6 toward the center side of the fuel hose along the hose axis (away from the end of the fuel hose) and the inner perimeter surface of the ring-shaped groove 6. Also, an engagement projection 12 is located on the outer perimeter surface of the hard, tube-shaped opposing member 11 and near the end of the opposing member 11.
In FIGS. 2a-2d, the process for inserting and fitting the ring-shaped groove 6 of the sealing ring 13 is not shown, but this process can involve, for example, using a typical mounting tool for a sealing ring or some other appropriate method. During this process, the ring-shaped groove 6 secures and aligns the sealing ring 13, thereby providing reliable alignment for the sealing ring 13. Also, the ring-shaped groove 6 includes projections and cavities such as the tongue piece 7 and the ring supporting section 8. The hose tube with the ring-shaped groove 6 is made of rubber or elastomer, and the sealing ring 13 can also be formed from a similar material and can have a cross-sectional shape corresponding to the shape of the ring-shaped groove 6. Therefore, the sealing ring 13 can be tightly fitted and embedded completely in the ring-shaped groove 6.
As shown in FIG. 2a, the hard, tube-shaped opposing member 11 is pressed into the opposing member insertion section 5. When the engagement projection 12 reaches the positions shown in FIGS. 2b and 2c, the engagement projection 12 applies a strong frictional force to the sealing ring 13 to prevent misalignment of the sealing ring 13. In extreme cases, the sealing ring 13 can drop out from the ring-shaped groove 6 without an engagement projection 12.
However, as shown in FIGS. 2b and 2c, the engagement projection 12 pushes the tongue piece 7, which is formed with a sloped surface overhanging over the ring-shaped groove 6, upward in the direction of arrow X. The force acting in the direction of arrow X is distributed at the sealing ring 13 to forces in the direction of arrow Y and arrow Z. Thus, the sealing ring 13 firmly resists the misalignment described above. Thus, the sealing ring 13 of the present invention does not become misaligned.
Furthermore, the sealing ring 13 tries to move to the right in FIGS. 2b and 2c (toward the center side of the fuel hose along the hose axis). However, the sealing ring 13 fits in the ring supporting section 8, which is indented toward the center side of the fuel hose along the hose axis. Thus, as long as the sealing ring 13 does not escape from the ring supporting section 8, the sealing ring 13 will not become misaligned. High pressure applied to misalign the sealing ring 13 results in a strong force applied to the sealing ring 13 to fit to the ring supporting section 8. As a result, the sealing ring 13 will not become misaligned.
The opposing member 11 can be pushed into the opposing member insertion section 5. When the opposing member 11 has been inserted deep enough, it is stopped by abutting the stopper 9, as shown in FIG. 2d. At this point, the engagement projection 12, which is disposed at or near the end of the opposing member 11, abuts the sealing ring 13 and is fitted in the ring-shaped groove 6. In this state, the sealing ring 13 is pushed outward in the radial direction by the engagement projection 12, thereby applying more pressure against the ring-shaped groove 6. As a result, adequate sealing properties can be provided even with the use of the low fuel permeability resin layer 10 on the inner perimeter surface of the ring-shaped groove 6.
The tongue piece 7 described above on the side wall of the ring-shaped groove 6 forms a cavity for supporting the sealing ring 13 similar to the ring supporting section 8 formed on the opposing side wall of the ring-shaped groove 6. Thus, in addition to the advantages described above, the presence of the tongue piece 7 in the ring-shaped groove 6 provides additional support for the sealing ring 13 by forming a ring supporting cavity. This additional support for the sealing ring 13 prevents misalignment of the sealing ring 13 effectively, especially toward the end side of the fuel hose along the hose axis of the ring-shaped groove 6.
According to another embodiment of the present invention, a fuel hose connection structure includes a fuel hose, a sealing ring, and an opposing member formed as a hard tube, as described above. The sealing ring is tightly fitted into a ring-shaped groove of the fuel hose. The hard, tube-shaped opposing member is inserted so that an expanded, ring-shaped engagement projection abuts the sealing ring. The engagement projections is located at an end or near the end of the opposing member on the outer perimeter surface of the opposing member.
In addition to the advantages described above, the fuel hose connection structure according to the present invention provides an easy-to-use structure that is simple and inexpensive without requiring any special increases in cost. Furthermore, as described above, the pipe connection section has low fuel permeability and good fuel sealing properties.
According to another embodiment of the present invention, the sealing ring can have a ring shape having fixed, belt-type axial width.
A sealing ring that is formed with a ring shape having a fixed, belt-type axial width provides a large contact surface with the inserted opposing member. Thus, good sealing properties are provided. Also, the sealing ring is firmly secured to the ring-shaped groove when the opposing member is inserted.
According to another embodiment of the present invention, the sealing ring can have an arcuate cross-sectional shape along an axis of the sealing ring and/or a ridge projecting outward in the radial direction on the outer perimeter surface of the sealing ring.
If the sealing ring is formed with an arcuate cross-sectional shape along an axis of the sealing ring, a flat cross-sectional shape is formed between the opposing member and the ring-shaped groove, with the sealing ring applying a force to restore its original arcuate cross-sectional shape. Thus, the ends of the sealing ring along the axis press strongly against the opposing member or the ring-shaped groove, thereby improving the sealing properties. If the axial cross-sectional shape of the sealing ring is arced outward in the radial direction so that the ends of the sealing ring along the axis project outward in the radial direction, the sealing ring is pressed strongly against the ring-shaped groove, thereby improving the sealing properties substantially.
Also, if a ridge projecting outward in the radial direction is located on the outer perimeter surface of the sealing ring, the ridge is pressed firmly against the bottom wall of the ring-shaped groove and pushes slightly into the bottom wall of the ring-shaped groove. Thus, even if the hose tube or the sealing ring deteriorates, high sealing properties can be maintained at the ridge.
According to an embodiment of the present invention, the sealing ring can be positioned so that the ridge described above is aligned with the apex of the ring-shaped engagement projection on the opposing member.
The ring-shaped sealing ring with a fixed belt-shape axial width receives firm sealing pressure when aligned with the engagement projection of the opposing member after the opposing member is inserted. A ridge can be positioned to align with the ring-shaped engagement projection on the opposing member, so that the pressure of the ridge on the bottom wall of the ring-shaped groove is especially adequate.
The above and other advantages of the invention will become more apparent in the following description and the accompanying drawings.